1. Field of the Invention
The present invention pertains to an inspection system for the internal surfaces of enclosed vessels, particularly coke drums and the like, wherein a combination of a distance measuring survey instrument and video camera are cooperatively operated to inspect the internal surfaces of the vessel for deterioration and distortion.
2. Background
Many enclosed vessels require, or desirably should undergo, periodic inspection to detect structural anomalies or other conditions which may eventually lead to vessel structural deterioration or failure. For example, it is desirable to frequently inspect the interior surfaces of vessels known as coke drums used in petroleum coking operations to determine if bulging or distortion of the drum surfaces has occurred and/or if other and visual signs of deterioration are present. Vessels such as petroleum coking drums may be on the order of twenty feet to thirty feet in diameter and fifty feet to seventy feet in height. These vessels are subjected to thermal and mechanical stresses which, without periodic monitoring, can lead to early and unexpected structural failure. One problem encountered in inspecting petroleum coke drums and similar vessels pertains to the fact that the exterior surfaces of these vessels are clad with an insulating blanket or other protective structure which prohibits easy visual inspection of bulges or similar distortions in the drum structure. Such bulges are usually indicators of structural deterioration of the drum.
Heretofore, for example, petroleum coke drums have been inspected by emptying coke from the drum, thoroughly washing and purging of the drum interior space and erecting a scaffolding in the interior of the drum so that inspection personnel may make essentially manual dimensional measurements to detect changes in shape of the drum structure, such as bulges in the cylindrical surface, which would indicate a weakness in the drum and possible early failure. Clearly, the time, expense and hazards associated with this type of inspection procedure are such as to bring forth the realization of a need to improve the inspection process. Similar types of vessels which are required or are desirably inspected from the interior should also benefit from a solution to the abovementioned problem.